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Abstract The band alignment of sputtered NiO on β -Ga 2 O 3 was measured by x-ray photoelectron spectroscopy for post-deposition annealing temperatures up to 600 °C. The band alignment is type II, staggered gap in all cases, with the magnitude of the conduction and valence band offsets increasing monotonically with annealing temperature. For the as-deposited heterojunction, Δ E V = −0.9 eV and Δ E C = 0.2 eV, while after 600 °C annealing the corresponding values are Δ E V = −3.0 eV and Δ E C = 2.12 eV. The bandgap of the NiO was reduced from 3.90 eV as-deposited to 3.72 eV after 600 °C annealing, which accounts for most of the absolute change in Δ E V −Δ E C . Differences in thermal budget may be at least partially responsible for the large spread in band offsets reported in the literature for this heterojunction. Other reasons could include interfacial disorder and contamination. Differential charging, which could shift peaks by different amounts and could potentially be a large source of error, was not observed in our samples.
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Structure, Stability, and Electronic Properties of the 2D van der Waals Selenophosphate LiGaP 2 Se 6
We report the two-dimensional (2D) bimetallic selenophosphate, LiGaP2Se6, prepared through direct combination reactions and P2Se5 flux methods. The material is a member of the broad class of van der Waals 2D materials of the type M2P2Q6 (M = metals). The structure was determined using single-crystal X-ray diffraction and refined in the chiral space group P3̅1c, with lattice parameters a = b = 6.2993(9) Å, c = 13.308(3) Å, α = β = 90°, γ = 120°. Differential thermal analysis indicated a congruent melting point at ∼458 °C. Optoelectronic properties were assessed using ultraviolet–visible (UV–vis) spectroscopy, showing a band gap of 2.01 eV, and photoemission yield spectroscopy in air (PYSA), which determined a work function of 5.44 eV. Notably, stability studies on LiGaP2Se6 revealed remarkable resilience despite its Li content, showing no structural changes after 2 weeks in ambient air or after soaking in a water/ethanol bath.
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- Award ID(s):
- 2305731
- PAR ID:
- 10627020
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- Inorganic Chemistry
- ISSN:
- 0020-1669
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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